SDF Text: Infinite layout loop

In v0.8.0, an infinite loop within the `layoutText()` method for SDF text can be triggered in certain cases when text wraps to a new line that can't fit within the height of a `contain: both` text node.

Offending commit: https://github.com/lightning-js/renderer/commit/2366aefbf93b92894b796e507275b74c3448d773